Quantitative depth profiling of ultrathin high-k stacks with full spectrum time of flight–secondary ion mass spectrometry
(Color online) Transient in pure (bulk) Si wafer obtained with a 250 eV beam for sputtering and a 15 keV beam for analysis.
(Color online) Profile of a 1.9 nm thick SiON layer on a Si substrate, obtained with a 150 eV beam for sputtering and a 15 keV beam for analysis.
(Color online) Full spectrum ToF-SIMS profile of the SiON/Si sample.
(Color online) Full spectrum ToF-SIMS profiles of the and HfSiON/SiON/Si samples.
(Color online) Overlaid full spectrum ToF-SIMS, HRBS, and pAR-XPS profiles of the SiON/Si sample.
(Color online) Overlaid full spectrum ToF-SIMS, HRBS, and pAR-XPS profiles of the HfSiON/SiON/Si sample. Same agreement is achieved for the sample (not shown).
(Color online) Overlaid full spectrum ToF-SIMS profiles of the HfSiON/SiON/Si sample obtained with a variation of . The full, dark lines represent the correct profile (identical to the profile presented in Figs. 4 and 6), and the light areas represent the possible composition variations due to the change of . Same behavior is observed for the other samples.
ToF-SIMS sensitivity factors obtained with the full spectrum protocol in the three samples studied in this work.
Layer thicknesses measured for the different samples, in nm. For SiON/Si sample, layer thickness was measured as the point of 66.6 at. % Si composition (Si half signal from SiON layer to Si substrate). For both other samples, hafnium silicate layer thickness was measured as the point of Hf half signal, and pedestal oxide layer thickness as the point of N half signal. Layer thicknesses were not measured with pAR-XPS since its depth scale was resulting from a fit to this of the two other techniques.
Composition of the hafnium silicate layer in the HfSiON/SiON/Si sample obtained with the three techniques, in at. %. These values were obtained on the center part of the layer, with a 0.5 nm exclusion margin on each side to avoid transient regions.
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